Owen's Notes

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Revision as of 18:36, 23 March 2020 by Oweng (Talk | contribs)

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Remote Login (23 March 2020)

The computers can be accessed remotely using SSH and VNC. Since I use Linux (Ubuntu) these instruction are for that OS.

To VNC into Helios, open a terminal and type the following command:

ssh -L 5902:helios.solar.pvt:20000 oweng@ovsa.njit.edu

I then open Remmina Remote Desktop Client. Make sure VNC is selected at the top left. Type in:


and enter the password when prompted.

The Helios display should now be visible.

Occasionally, the VNC connection will be lost. If this occurs the following procedure need to be performed.

From a new terminal window type:

ssh -L 8887:helios.solar.pvt:22 oweng@ovsa.njit.edu

From another terminal issue the command:

ssh -p 8887 sched@localhost

Now type in:


Now restart the VNC client.

Phase Calibrations (23 March 2020)

Phase calibrations are to be performed every day when possible.

Access the Helios computer.

On the terminal window make sure that the ipython: /home/user tab is selected.

There should be a prompt as follows: pipeline:~>

At the prompt type the following command:

python /common/python/current/calwidget.py

The following window will open up:

The calwidget window.

In the date box near top right of the window type in or use the up and down arrows to select the previous days date and hit enter.

Click on the first available scan that does not suffer from a Windscram. Windscrams are marked in red. If a windscram occurred for less than 20% of the scan then it will be marked in yellow and may still be usable. The example below shows a windscram at 22:14:05.

The calwidget window with windscram shown at 22:14:05 highlighted in red.

Select the earliest calibration that does not have a windscram, and then click on 'Analyze as Refcal'. The Sigma map should new be populated as shown below:

The calwidget window with sigma map. It also shows power and phases for Antenna 1 and Frequency Band 12.

Update Antenna Pointing (17 March 2020)

Access the Pipeline Computer.

From the terminal, start ipython:

ipython --pylab

Import the calibration and Time libraries:

import calibration as cal

from util import Time

Load up the solar pointing scans for a given date and time.

x,y,qual=cal.solpntanal(Time('2020-03-17 18:30'))

The above command will load the scans from the 17 March 2020 18:30 UT.

To view the beam widths as a function of frequency for each antenna and polarisation:


An example of the X-beam widths for each antenna
An example of the Y-beam widths for each antenna

To obtain the pointing offsets:


This will display the offsets for each antenna and feed. Ideally the offsets should be at zero. If particular antennas significantly deviate from zero then a correction can be made.

For example, the following command will adjust the pointing offsets for antennas 6 to 8, 10 and 13:

cal.offsets2ants(Time('2020-03-17 18:30'),xoff,yoff,antst='ant6 ant7 ant8 ant10 ant13')

The newer antennas with the alt-az drives that have had tracking updated will need to be rebooted. From the Schedule Window issue the commands:

reboot 1 ant6-8

tracktable sun_tab.radec 1 ant6-8

track ant6-8

The antenna pointing adjustment is typically performed once per month.

Helios Displays

The Schedule window show the currently running schedule as shown below.

The Schedule Window

The left side of the window shows each of the scripts that is to be run. The orange bar shows the task that is currently being run.

The right side of the window shows each command that is to be run in the current script.

At the bottom of the window are a series of buttons. The STOP button will stop at the current script. Once stopped, the remaining buttons will become active.